Center post guided die cushion assembly



Dec. 2, 1969 J. HOENIG CENTER POST GUIDED DIE CUSHION ASSEMBLY FiledJan. 22, 1968 VENTOR.

A| P||. a 1A 4 wbr/www. IMHHIIHMU, A1; @Half Y W @MMM WAH /y/ f4 M! .rw,4 if l /fH/ i .lvwdwwwvm INAVITIMANIHIIH l lill IJIII. i j V 1Q z /l l1V l M Il United States Patent O U.S. Cl. 267--1 4 Claims ABSTRACT OFTHE DISCLOSURE A center post guided die cushion assembly for a press orthe like. The center post is supported by a plate that is aixed acrossone end of a pocket that contains the die cushion assembly and that liesbeneath the press bolster plate. The center post extends concentricallythrough the cushioning cylinder and slidably guides the reciprocatingmovement of the piston.

BACKGROUND OF THE INVENTION This invention relates to an improved centerpost guided die cushion assembly for a press or the like.

The use of air or hydraulic die cushions for applying pressure to thedie blank holder or pad of a press are well known. With this type ofconstruction, pressure is generally applied from the piston of the diecushion to the respective press component through die or pressure pins.Since the pistons of these cushions experience considerable loading, itis essential that their movement be guided over a relatively large areato preclude any binding under the load and attendant damage to the diecushion. Although it previously was proposed to guide such pistons atthe area of contact between the piston and cylinder, this method ofguiding has several defects. The primary defect in such a guidingarrangement is that the -piston seals are subjected to considerableloading resulting in premature failure. It, therefore,` has been morerecently proposed to employ a center post guiding arrangement for thepiston. With this type of die cushion assembly, a center post extendscoaxially through the cylinder and slidably supports the piston. In sucha construction, it is necessary to insure a rigid support for the upperend of the center post. Such support was heretofore provided by directlyattaching this center post to the bolster plate of the press, but thisalso has certain disadvantages. If the center post is `directlyconnected to the bolster plate, setup is diflicult and more timeconsuming, In addition, the die cushion must be relocated every time thebolster plate is changed, which can occur frequently. There is alsoconsiderable difliculty in correctly locating the bolster plate withrespect to the die pocket and other components of the press which canresult in binding of the die cushion center post.

It is, therefore, a principal object of this invention to provide animproved center post guided die cushion assembly.

It is another object of this invention to provide a center -post guideddie cushion assembly wherein the center post is supported independentlyof the lbolster plate of the press.

BRIEF SUMMARY OF THE INVENTION A center post guided die cushion assemblyembodying this invention is adapted to be supported as a unit in apocket beneath the bolster plate of a press or the like. The die cushionassembly comprises a cylinder defining a cylinder bore in which aIpiston is reciprocally supported. A support plate is adapted to extendacross the die cushion pocket and is adapted to be xed to the press orthe like. A center post is affixed at one of its ends to the supportplate. The center post extends into 3,481,592 Patented Dec. 2, 1969 thecylinder bore and is affixed at its other end to the cylinder. Means onthe center post and on the piston guide the piston and cylinder forrelative reciprocation independently of the cylinder bore.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a longitudinal crosssectional View of a portion of a press incorporating a center postguided die cushion embodying this invention and taken generally alongthe line 1-1 of FIGURE 2;

FIGURE 2 is a top plan view of the press shown in FIGURE 1, with thebolster plate removed to more clearly show the construction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, thereference numeral 11 indicates generally a center post guided diecushion assembly embodying this invention. The die cushion assembly 11is particularly adapted for use in presses, which may be of any knowntype. The press, which is illustrated partially in the drawings,includes a bolster plate 12 that overlies a die cushion pocket 13 formedin the base of the press by means of a pair of vertically extendingplates 14 and 15 that are aii'ixed to cross plates 16 and 17. An upperplate 18 extends across the plates 14, 15, 16 and 17 and serves toprovide support for the lbolster plate 12. In ya like manner, a bottomplate 19 extends across the lower edge of the plates 14, 15, 16 and 17and at least partially across the lower end of the die cushion pocket13.

Referring now to the construction of the die cushion assembly 11, it iscomprised of a cylinder 21 that defines a cylinder bore 22 that is openat its upper end and which is closed at its lower end by an integral endwall 23. The cylinder end wall 23 is connected in any suitable manner toa supporting base 24. The supporting base 24 is affixed with respect tothe press plate 19 by means of socket headed bolts 25.

A piston 26 is supported for reciprocation within the cylinder bore 22.The piston 26 carries an annular seal 27 at its lower end to provide auid tight seal between the piston 26 and the cylinder bore 22. Theextreme upward position of the piston 26 within the cylinder bore 22 islimited 'by an annular stop ring 28 that is aflixed to the upper end ofthe cylinder 21 by means of socket headed bolts 29.

The piston 26 defines a hub or pilot portion 31 that has cylindricalbore 32. Antifriction bushings 33 and 34 are xed in circumferentialrecesses 35 and 36, respectively, formed at opposite ends of the bore32. A center post 37 extends upwardly through the bore 32 and slidinglyengages the bushings 33 and 34 to guide the reciprocation of the piston26. The lower end 0f the center post 37 extends through an opening 38 inthe cylinder wall 23 and is hield in :place by a nut 39 that is threadedonto its tapped lower end 41.

In die cushions of the type described, the seal 27 of the piston vdoesnot take any of the guiding forces of the piston 26 and thus, this sealis not subjected to any undue wear since the center post 37 accomplishesthe guiding function. With this type of assembly, it previously had beenthe practice to support the upper end of the center post through adirect connection to the bolster plate 12 of the press, which as hasbeen noted, requires relocation of the upper center post support whenthe bolster plate 12 of the press is changed. Certain otherdisadvantages also are attended with the upper support of the centerpost by the bolster plate. In the described die cushion, the center post37 is supported at its upper end independently of the bolster plate 12in a manner now to be described.

The upper end of the center post 3'7 is formed with a bored opening 42that receives a pilot portion of a top support plug 43. The supportIplug 43 is fixed, as by bolts 44 to an upper support plate 45 thatextends across the upper end of the die cushion pocket 13. The plug 43also may have a :pilot portion that fits into a bored hole in thesupport plate 45. The plate 45 is accurately located with respect to thepress assembly and when so located is xed in position by socket headedbolts 46 that are threaded into supporting blocks 47 which are, in turn,fixed to the respective plates 14 and 15 of the press assembly. Thisconstruction permits accurate location of the upper support for thecenter post 37 and permits the center post 37 to be supported at itsupper end independently of any direct connection to the bolster plate12.

The piston 26 is abuttingly engaged at its upper end by a pressure plate51. The pressure plate 51 is contacted by pressure or die pins 52 of thepress which pins extend through bores 53 formed in the bolster plate andlike bores 54 formed in the top supporting plate 45. As is well known inthis art, the pressure exerted by the piston 26 is transmitted throughthe pressure plate 51 to the pins 52 and to the corresponding componentof the press. Hydraulic or pneumatic pressure for this purpose isintroduced to a cavity 55 formed between the piston 26 and cylinder bore22 by means of a pressure conduit 56.

In order to lubricate the bushings 33 and 34, transversely extendinglubricating passages 57 and 58 are formed in the center post 37. Thepassages 57 and 58 are intersected by an axially extending passage 59that opens through the lower end of the center post 33. Any suitablelubrication pressure conduit may be connected to this lower end of thepassage 59 for lubrication of the bushings 33 and 34.

`In order to preclude the ingress of chips, dirt or other foreign matteronto the piston seal 27, a cylindrical shroud ring 61 is affixed to thepressure plate 51 in any suitable manner. The shroud ring extendsdownwardly closely adjacent the outer periphery of the stop ring 28 andupper edge of the cylinder 21. In the uppermost position of the piston26 as illustrated in FIGURE l, this shroud ring depends slightly belowthe aforenoted elements. Hence, a labyrinth type seal is provided forprecluding the entry of foreign matter onto the moving components of thecushion assembly 11. In addition, downward movement of the pressureplate 51, piston 26 will cause a decrease in the volume 62 between theshroud ring 61 and piston 26 above the stop ring 28. Hence, air will bedriven from the area 62 tending to drive out any foreign particles whichmay have entered past the shroud ring 61.

While it will be apparent that the preferred embodiments of theinvention disclosed are well calculated to fulfill the objects abovestated, it will be appreciated that the invention is susceptible tomodication, variation and change without departing from the proper scopeor fair meaning of the subjoined claims.

What is claimed is:

1. A center post guided die cushion assembly adapted to be supported asa unit in a pocket beneath the bolster plate of a press or the likewithout any direct connection to the bolster plate, said die cushionassembly comprising a cylinder dening a bore, a piston reciprocallysupported in said cylinder bore, a support plate adapted to extendacross one end of the die cushion pocket and adapted to be afixed to thepress or the like, the center post aixed at one of its ends to saidsupport plate, said center post extending into said cylinder bore, meansfor aixing the other end of said center post relative to said cylinder,and means on said center post and on said piston for guiding thereciprocation of said piston within said cylinder bore substantiallyindependently of said cylinder bore.

2, A center post guided die cushion assembly as set forth in claim 1wherein the center post has a pilot portion received in a bore in thesupport plate for assisting ir locating said center post with respect tosaid support p ate.

3. A center post guided die cushion assembly as set forth in claim 1wherein the support plate is positioned adjacent the press bolster plateand is affixed in an accurate location with respect to the pocket forpermitting interchange of the bolster without necessitating relocationof the support for the one end of said center post.

4. A center .post guided die cushion assembly as set forth in claim 1wherein the cylinder is open at its upper end, and further including ashroud ring aixed for reciprocation with the piston, said shroud ringbeing juxtaposed to said open end of said cylinder and extendingdownwardly therefrom when said piston is in its extreme upper position,movement of said piston and said shroud ring downwardly being effectiveto drive foreign particles from the volume surrounding said piston.

References Cited UNITED STATES PATENTS JAMES B. MARBERT, PrimaryExaminer

